1. Field of the Invention
The present invention relates to plating pretreatment apparatus and method for a cylinder block that perform a plating pretreatment of a cylinder inner wall surface of a cylinder in a cylinder block by sealing one end of the cylinder inner wall surface and circulating a treatment liquid.
2. Description of the Related Art
There are many cylinder block manufacturing methods that involve coating the cylinder inner wall surface with a plating film.
For example, as shown in FIG. 1, the technique according to Patent Document 1 (Japanese Patent Laid-Open No. 9-13193) includes a plating pretreatment step in which a required amount of treatment liquid is supplied to a cylinder inner wall surface 102 of a cylinder 101 in a cylinder block 100 by means of a pump 103, and then the pump 103 is stopped and valves 104 and 105 are closed to retain the treatment liquid in the cylinder 101 for a predetermined time, thereby performing a plating pretreatment. In the following plating step, one end of the cylinder inner wall surface 102 is sealed with a seal jig (not shown in FIG. 1), and then a plating solution is supplied into and circulated in the cylinder 101 by means of the pump 103 to perform a plating treatment.
Furthermore, as shown in FIG. 2, the techniques disclosed in Patent Documents 2 and 3 (Japanese Patent Laid-Open Nos. 2000-192284 and 2000-192285) include a plating pretreatment step in which one end of the cylinder inner wall surface 102 of the cylinder block 100 is sealed with a seal jig 106, a treatment liquid is introduced to the cylinder inner wall surface 102, and a voltage is applied between an electrode 107 and the cylinder block 100 to perform a plating pretreatment.
However, in the plating pretreatment described in Patent Document 1, reaction gas produced in the plating pretreatment flows outside the cylinder block 100 because one end of the cylinder inner wall surface 102 is open. If the reaction gas is a toxic gas, it may corrode the equipment or adversely affect the health of operators.
In the plating pretreatments described in Patent Documents 2 and 3, reaction gas 108 produced in the plating pretreatment may be accumulated in the vicinity of the cylinder inner wall surface 102 of the cylinder 101 to compromise electrical conduction or hinder filling with the treatment liquid, and the plating pretreatment may be inadequate.